Dr. Park Dietz appeared as a forensic-psychiatry witness for the plaintiffs in the civil trial during a contentious admissibility hearing concerning expert witnesses. On direct examination by Peter Gelblum, Dietz described his education, forensic-psychiatry training, academic and clinical positions, and work involving violence prevention; Dan Leonard stipulated to his qualifications as a forensic psychiatrist.
Park Elliot Dietz is a forensic psychiatrist who has consulted or testified in many of the highest-profile US criminal cases, including those of spousal killer Betty Broderick, mass murderer Jared Lee Loughner, and serial killers Joel Rifkin, Arthur Shawcross, Jeffrey Dahmer, Ted Kaczynski, Richard Kuklinski, the D.C. sniper attacks, and William Bonin.